Relay



H. ZIEBOLZ Dec. 3, 1940.

RELAY Filed April 12. 1937 a 1 i i 1 I IIIIIIIII I I I 1.0 PRESSURE(IN/T6 8 MAG/T/ r005 OF PRIMARY MPULSE- In veptar:

Patented Dec. 3, 1940 UNITED STATES RELAY Herbert Ziebolz, Chicago,Ill., assignor to Aslrania Regulator Company, Chicago, 111., acorporation oi Illinois Application April 12, 1937, Serial No. 136,515

9 Claims. (Cl. 137-153) This invention relates to relays, moreparticularly to relays of the pressure fluid type.

Relays are used to convert primary impulses,

such as forces, or positions, into secondary impulses of difierentmagnitude to be used. for various purposes, such as operating measuringinstruments, control apparatus, or the like.

To insure a constant and correct relation between the primarycontrolling impulses and the 0 secondary impulses created by the relaythe latter may also be applied to act on the relay in addition, oropposition, to the controlling impulses, e. g., in such a way as topartly or entirely coun terbalance the primary impulses.

As far as I am aware, it has heretofore been the practice to derive suchadditional influences from a positive pressure set up in a section of aconduit adjoining a constriction through which a pressure fluid flowscontrolled by the said relay. The pressure set up in the said sectionconstitutes also the secondary impulse, used further for measuring andcontrolling purposes.

It is an object of this invention to provide an improved relay of simpleconstruction having a high sensitivity responding to and creatingimpulses of a wider difference in magnitude than heretofore.

Inasmuch as a pressure, or impulse, derived in the conventional way hasa definite and positive value which is greater than zero, as will behereinafter explained in detail, the range of the relay is limited toprimary impulses having a definite and positive minimum value. Primaryimpulses of a lesser magnitudewill not operate the relay.

According to this invention, the disadvantages of the conventional typeof relay are overcome by deriving the secondary impulse-pressure at apoint of the conduit within the suction range of a constriction, wherebyeven negative, 1. e., suction pressure values will be attained.

Objects and advantages of this invention will appear from aconsideration of the description which follows with the accompanyingdrawing showing embodiments of the invention for illustrative purposes.It is to be understood that this description is not to be taken in alimiting sense,

the scope of the invention being defined in the appended claims.

Referring to the drawing: Fig. 1 is a diagrammatic illustration, partlyin section, of a relay mechanism Fig. 2 is a diagrammatic illustrationof the v pressure conditions existing at a constriction;

trating the pressure conditions in the neighbor- Figs, 3 and 4 arediagrams-toillustrate the operation of the invention; and

Fig. 5 is a modified form of relay of Fig. 1 shown partly in section.

Pressure fluid from a source (not shown) 'is 5 flowing through a-conduitill having a constriction therein, shown as being a Venturi tube II. Thefiow of pressure fluid through the conduit i0 is controlled by a relayshown as having a controlimpulse receiving member, lever i2, pivotally10 mounted at l3 and controlling the discharge of fluid from a port H bymeans of a baflle plate IS. The opening of the discharge port is afunction of the space 8" between the bafiie plate and the port opening.i5

-The position of the control member-of the relay, the lever I2, iscontrolled by a primary impulse, such as a pressure acting within thediaphragm chamber Hi.

In opposition to the control impulse there is 20 shown to act upon therelay a secondary pressure-impulse taken at the throat of the Venturitube and acting on a second diaphragm i'l within a diaphragm chamber R8.The size of this diaphragm determines the ratio between the pri- 25 maryimpulses acting on the relay and the secondary impulses set up by thefluid at the throat of the Venturi tube. The smaller the diaphragm hoodof a constriction in a conduit.

.A conduit l0 having a constriction in the form of an orifice plate 23therein is tapped at points A, B and C and the pressure existing atthese 5 points measured by gages 24, 25 and 26, The pressure in front ofthe orifice plate is indicated by ing decrease in pressure, l

sure limit is at about one-fifth of the pressureva'lue pa.

As diagrammatically indicated by the arrows,

the fluid is constricted to a narrow path when passing through theorifice plate, forming a so- I ing on the relative size of the orifice.

It has heretofore been the practice to connect the diaphragm chamber iiito a point C of the conduit I0. The characteristics of the relay of theknown type are illustrated by the dotted curves in Figs. 3 and 4.

In Fig. 3 the ratio of the pressures upstream and downstream of theconstriction is plotted against the stroke s of the battle plate. It isseen that for a closed discharge port, corresponding s=0 the pressureratio will be 1.0. When the port is opened the ratio will graduallydecrease according to the dotted line and approach the value .2.It-appears therefrom that even if there is no controlling impulse actingon the relay there will be a force exerted by the diaphragm l1, tendingto maintain the port I4 open and resisting a change of this condition.Controlling impulses of a lesser magnitude than the force of thediaphragm I! will therefore have no eflect on the relay and not beconverted into secondary impulses. The dotted line in Fig; 4will-illustrate the foregoing.

In Fig. 4 the secondary impulses expressed in terms of pressure 121, areplotted against primary controlling impulses. It appears that at acontrolling impulse of zero or small magnitude there will always be a'secondary impulse of the mag-.

nitude of .2 pressure unit, thereby rendering the relay nonresponsive tosmall control forces.

According to this invention the secondary impulses are taken at a pointB within the "vena vcontracta" or suction-range of the constriction, asshown in Fig. 1.

Turning againto Fig. 3, it is easily understood that the pressure P2will become zero, and even attain negative values when the pressure p,becomes a suction pressure as' indicated by the solid curve.correspondingly, the influence of the diaphragm I! on the control memberwill be zero and the secondary impulse zero when the control impulse iszero. This condition is illustrated by the solid curve in Fig. 4extending to the zero point.

The operation of the relay shown in Fig. 1

will now be easily understood. Assuming a control impulse acting on thecontrol member sud- The pressure acting on the denly becomes zero.

- diaphragm i! will at this instant tend to openthe port M therebyincreasing the flow through conduit Ill. The increasing flow reduces thepressure existing within the range of the vena contracta Ill will beincreased to cause a negative pressure to act on the diaphragm l1.thereby operating the relay to throttle the flow until is obtained. I

It is also apparent that if an upwardly directed impulse is applied tothe relay lever an equal and oppositely directed force will be exertedby the diaphragm l1 and the gage 19 will .indicate suction pressure; I

A modified form of the relay is shown in Fig. 5. The conduit I0" isprovided with a nonv'ariable constriction shown as being an orificeplate I I" and a variable constriction, or throttle, shown as being agate-valve I5". sure impulse is takenat a point within the venacontracta or suction range of the orifice-plate II" to act in the sameway on a diaphragm H" as hereinbefore explained. The device for exertthezero position ing primary impulses on the lever I2" is not- Thesecondary presherein shown and described. Other types of flow resistingmeans may be employed than herein shown and described. The constantresistance offered by a long conduit may be utilized, for instance, asis well known in the art, or other changes may be made without departingfrom the scope of the invention. .Moreover,-it is not indispensable thatall the features of the invention be used conjointly, since they may be.employed advantageously in various combinations and sub-combinations.

What is claimed is:

1. Pressure fluid relay comprising, in combination, a conduit having adischarge port; a constriction in said conduit; a member responsive toan outside-control impulse and arranged to vary the discharge from saidport for varying the pressure within the suction range of saidconstriction in responseto said outside control impulse; and meansresponsive 'to a pressure taken at the suction range of saidconstriction and connected to act on said member in opposition to thecontrolling impulse.

2. Pressure fluid relay comprising, in combination, a conduit; a fixedconstriction in said conduit; a variable constriction downstream of saidflxed constriction; means responsive to an outside primary impulse foradjusting said variable constriction; and a secondary impulse pressureconduit connected to said flrst named conduit within the suction rangeof said fixed constriction,

-' whereby the secondary impulse pressure becomes a function of theprimary impulse, ranging from suction pressure values upwards.

and a secondary impulse pressure conduit connected to said firstnamedconduit within the suction range of said fixed constriction,whereby the secondary impulse pressure'becomes a function of the primaryimpulse, ranging from suction pressure values upwards.

4. Pressure fluid relay comprising, in combination, a conduit: 9. fixedand a variable constriction'therein; means responsive to an outsideprimary impulse for adjusting said variable con striction; and asecondary impulse pressure conduit connected to said firstnamed conduitwithin the suction rangev of' theconstriction arranged upstreamrelatively to the second con- .becomes afunction of the primary impulse,

ranging from suction pressure values upwards.

5. Pressure fluid relay comprising. in combination, a conduit; aconstriction in said conduit; a variable throttle in said conduitdownstream or said constriction; means responsive to an outside primaryimpulse for adjusting said throttle; and a secondary impulse pressureconduit connected to the said first named conduit within the suction.

range ,of said constriction, whereby the impulse pressure becomes afunction of the primary impulse.

6. Pressure fluid relay comprlsinain combination, a conduit having adischarge port; a constriction in said conduit; a movable baffle platearranged to control the discharge of pressure fluid through said port,means responsive to an outside impulse and connected to move'said bailleplate for varying the pressure within the suction range of saidconstriction said outside impulse; and means responsive to a pressuretaken at the suction range oi. said constriction and connected to acton' said baflie plate.

'7. Pressure fluid relay comprising, in combination, a conduit; aVenturi tube in said conduit; a discharge throttle in said conduit;means responsive to an outside throttle for varying the in response to 7control impulse and con-' tube in response to said control impulse;' anda diaphragm acted upon by a pressure taken at the throat of said Venturitube and connected to act,

in opposition to said impulse means. i

8. Pressure fluid relay comprising, in combination, a conduit, anorifice plate in said conduit; adischarge throttle in said conduit;means responsive to an outside control impulse and connected to adjustsaid throttle for varying the pressure within the suction range of saidorifice plate in response to said control impulse; and a diaphragm actedupon by a pressure taken at a point .01 the conduit within the venaconstrictai created by said orifice plate and connected to act inopposition to said impulse means. 9. Pressure fluid relay comprising aconduit; a non-variableand a variable constriction therein; meansresponsive to an outside'primary im-,

pulse for adjusting said variableconstriction for.

varying the pressure within the suction range of said non-variableconstriction in 'response to said primary impulse; and means responsiveto a pressure taken at the suction range of said nonvariableconstriction and connected to act in.

opposition to said impulse means whereby a pressure taken within thesuction range or said nonvariable constriction becomes a function of thecontrolling impulse.

HERBERT ZIEBOLZ.

